Wireless data communication system and method

ABSTRACT

A data communication system including a least one encoder and one decoder. The encoder encodes a received input signal into encoded output data. The data communication system includes a data communication network coupled to at least one encoder, wherein the data communication network communicates the encoded output data from the encoder to the decoder. The decoder decodes the encoded output data to generate a rendition of the input signal. The system is characterized in that the data communication network is configured to function according to joint source channel coding (JSCC). Moreover, the encoder and the decoder are configured to employ an hierarchical data structure for representing data to be communicated from the encoder to the decoder.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation U.S. application Ser. No. 17/380,718,filed Jul. 20, 2021, which claims the benefit of and priority to UKPatent Application No. 2007773.1, filed May 25, 2020, the entiredisclosures of which are incorporated herein by reference in theirentireties.

1. TECHNICAL FIELD

The present disclosure relates to wireless data communication systems,for example to wireless data communication systems that communicateimage or video data when in operation. Moreover, the present disclosurerelates to methods of (namely methods for) using aforesaid wireless datacommunication systems to communicate image or video data. Furthermore,the present disclosure relates to a computer program product comprisinga non-transitory computer-readable storage medium havingcomputer-readable instructions stored thereon, the computer-readableinstructions being executable by a computerized device comprisingprocessing hardware to execute the aforesaid methods.

2. BACKGROUND

It is well known to communicate image and video data via wirelesscommunication links, for example via satellite distribution of videocontent to domestic satellite receivers whose antennae are mounted toexterior walls of domestic premises (so-called “satellite TV”).Moreover, various data formats are employed when communicating data viathe wireless communication links; for example, data formats such asH.264, MPEG2 and MPEG4 are often employed.

A technical problem arises when the aforesaid wireless communicationlinks are more spatially local to a given region, and where the wirelesscommunication links include various intermediate relay nodes (forexample, wireless peer-to-peer networks). Problems such as wirelesssignal fading, ghosting due to signal reflection and interference fromextraneous wireless radiation emitters can cause a much high bit errorrate than encountered with aforesaid satellite data communication links.Such spatially local wireless communication links are also susceptibleto having operating parameters that temporally dynamically vary,especially when sources of wireless signals are mobile, for example arevehicle-mounted or are airborne.

Companies specializing in conveying image data via wireless datacommunication links are known, for example a company Amimon Ltd., basedin Israel. In a patent application WO2019/220433A1 (“Joint SourceChannel Coding with H.264 Video Compression”; Applicant Amimon Ltd.(IL)), there is disclosed a wireless video transmission systemcomprising:

-   -   a coarse compression module to compress a video frame and to        generate coarse data of the video frame;    -   a coarse decompression module to generate a coarse frame        information from the coarse data;    -   a distortions extractor to generate coarse distortions from the        coarse frame information and from the video frame;    -   a refinement data encoder to generate refinement data from the        coarse distortions based on the coarse frame information; and    -   a data combining and modulation module to combine and transmit        the coarse data and the refinement data.

It is known that wireless video transmission systems which combine a useof joint source channel coding (JSCC) with known compression blocktechniques including compression standards such as, for example, H.265,potentially suffer from bandwidth overhead. For example, a system thatcombines H.265 data with “analog” refinement data is susceptible toemploying “coarse” bins and “fine” bins where the coarse bins are usedfor sending H.265 data (including interframe prediction) and the finebins are used for sending the data for memoryless refinement of thereceived image. The analog refinement potentially hasvideo-content-dependent power, and potentially suffers from additivenoise and therefore, it may be desired to apply avideo-content-dependent gain to bring the transmitted power to thehighest level available by hardware capabilities and the radioregulation. However, a drawback of using content-dependent gain is thatthe gain should be conveyed to the receiver, and the message whichdescribes that gain, creates a bandwidth overhead.Video-content-dependent gain may optionally be applied to single blocks(that is, each block will have a different gain), or to group of blocks(that is, each group will have different gain, but all the blocks in thegroup will have the same gain).

Bandwidth overhead in video transmission systems combining use of knowncompression block techniques (for example, H.264 or H.265) with JSCC maybe reduced, optionally eliminated, by utilizing information associatedwith the coarse data to generate control data for the refinementencoder, where the refinement encoder generates refinement data whichmay be transmitted to a video receiver for memoryless refinement of avideo image. The transmission side may include a refinement encoderwhich may be adapted to perform a two-dimensional DCT transform oncoarse distortions which may be in the form of error frames (in thepixel domain) or in the form of quantization errors of DCT tapsgenerated from the coarse data to generate DCT taps for each block. Therefinement encoder may additionally calculate the block energy to applya gain to the coarse distortions DCT taps based on the power of thecoarse DCT taps. Alternatively, the refinement encoder may estimate aprobability density for the coarse DCT taps which may then be used toentropy encode the coarse distortions DCT taps. A compander may be usedto apply non-linear gain to the DCT taps of the refinement encoder.

Implementations of JSCC are described in a technical publication“Handbook_Image_Video_Processing”, and in particular: “Chapter 1: JointSource-Channel Coding for Video Communications” (authors Fan Zhai,Yiftach Eisenberg, and Aggelos K. Katsaggelos)http://users.eecs.northwestern.edu/˜fzhai/publications/Handbook_Image_Video_Processing_bookchapter.pdf

However, such known approaches based on JSCC do not provide asufficiently low latency performance for many applications of use, thatrequire substantially immediate image communication from a given sourceto a given recipient. Although JSCC seeks to combine source datacompression with transmission channel compression and forward errorcorrection (FEC) functionality to provide improved data transmissionwith less errors when transmission channel dropout, fading andinterference are likely to be encountered, it is desirable to provide ayet further improved performance to cope with performance requirementsfor many applications of use situations.

SUMMARY

The present disclosure seeks to provide an improved an improved datacommunication system that are less affected by objective technicalproblems as described in the foregoing.

According to a first aspect, there is provided a data communicationsystem including a least one encoder and at least one decoder,

-   -   wherein the at least one encoder, when in operation, encodes an        input signal received thereat into encoded output data;    -   wherein the data communication system includes a data        communication network that is coupled to at least one encoder,        wherein the data communication network, when in operation,        communicates the encoded output data from the at least one        encoder to the at least one decoder;    -   wherein the at least one decoder, when in operation, decodes the        encoded output data to generate a rendition of the input signal,    -   characterized in that    -   the data communication network is configured to function        according to joint source channel coding (JSCC);    -   the encoder and the decoder are configured to employ an        hierarchical data structure for representing data to be        communicated from the at least one encoder to the at least one        decoder, wherein the hierarchical data structure includes a base        layer and one or more enhancement layers with associated        residual data, wherein the base layer is capable of providing a        coarse rendition of the input signal at the at least one        decoder, and the one or more enhancement layers and their        associated residual data are useable when received at the least        one decoder to enhance the coarse rendition to render the input        signal at a high level of quality than the coarse rendition; and    -   the at least one encoder is operable selectively to drop sending        parts of data of the one or more enhancement layers and their        associated residual data in response bandwidth limitations,        ghosting, interference and/or data errors arising in the data        communication network.

The invention is of advantage in that using a hierarchical structure torepresent data in the encoded output data communicated pursuant to JSCCfrom the at least one decoder to the at least one decoder is able torender the system better able to cope with signal fading, datacorruption, data loss, ghosting and other types of data degradationarising in the data communication network.

Optionally, in the data communication system, the at least one encoderis configured to send base layer data of a given image frame to the atleast one decoder to decode concurrently with the at least one encodercomputing enhancement layer data of the given image frame to sendsubsequently to the at least one decoder, thereby reducing a latency ofdata communication arising when communicating from the at least oneencoder to the at least one decoder.

Optionally, in the data communication system, the at least one encoderis configured to drop sending enhancement layer data and resend baselayer data of a given image frame in an event that a first transmissionof the base layer data of the given image frame is corrupted whentransmitted from the at least one encoder to the at least one decoder.

Optionally, the system is configured to spread data of a givenIntra-frame of the input signal into a plurality of frame durations whencommunicated from the at least one encoder to the at least one decoder.

According to a second aspect, there is provided a method of operating adata communication system including a least one encoder and at least onedecoder,

-   -   wherein the at least one encoder, when in operation, encodes an        input signal received thereat into encoded output data;    -   wherein the data communication system includes a data        communication network that is coupled to at least one encoder,        wherein the data communication network, when in operation,        communicates the encoded output data from the at least one        encoder to the at least one decoder;    -   wherein the at least one decoder, when in operation, decodes the        encoded output data to generate a rendition of the input signal,    -   characterized in that the method includes:    -   configuring the data communication network to function according        to joint source channel coding (JSCC);    -   configuring the encoder and the decoder to employ an        hierarchical data structure for representing data to be        communicated from the at least one encoder to the at least one        decoder, wherein the hierarchical data structure includes a base        layer and one or more enhancement layers with associated        residual data, wherein the base layer is capable of providing a        coarse rendition of the input signal at the at least one        decoder, and the one or more enhancement layers and their        associated residual data are useable when received at the least        one decoder to enhance the coarse rendition to render the input        signal at a high level of quality than the coarse rendition; and    -   configuring the at least one encoder, when in operation,        selectively to drop sending parts of data of the one or more        enhancement layers and their associated residual data in        response bandwidth limitations, ghosting, interference and/or        data errors arising in the data communication network.

Optionally, the method further includes configuring the at least oneencoder to send base layer data of a given image frame to the at leastone decoder to decode concurrently with the at least one encodercomputing enhancement layer data of the given image frame to sendsubsequently to the at least one decoder, thereby reducing a latency ofdata communication arising when communicating from the at least oneencoder to the at least one decoder.

Optionally, the method further includes configuring at least one encoderto drop sending enhancement layer data and resend base layer data of agiven image frame in an event that a first transmission of the baselayer data of the given image frame is corrupted when transmitted fromthe at least one encoder to the at least one decoder.

Optionally, the method further includes configuring the system to spreaddata of a given Intra-frame of the input signal into a plurality offrame durations when communicated from the at least one encoder to theat least one decoder.

According to a third aspect, there is provided a computer programproduct comprising a non-transitory computer-readable storage mediumhaving computer-readable instructions stored thereon, thecomputer-readable instructions being executable by a computerized devicecomprising processing hardware to execute a method of the second aspect.

Additional aspects, advantages, features and objects of the presentdisclosure would be made apparent from the drawings and the detaileddescription of the illustrative embodiments construed in conjunctionwith the appended claims that follow.

It will be appreciated that features of the present disclosure aresusceptible to being combined in various combinations without departingfrom the scope of the present disclosure as defined by the appendedclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

The summary above, as well as the following detailed description ofillustrative embodiments, is better understood when read in conjunctionwith the appended drawings. For the purpose of illustrating the presentdisclosure, exemplary constructions of the disclosure are shown in thedrawings. However, the present disclosure is not limited to specificmethods and instrumentalities disclosed herein. Moreover, those skilledin the art will understand that the drawings are not to scale. Whereverpossible, like elements have been indicated by identical numbers.

Embodiments of the present disclosure will now be described, by way ofexample only, with reference to the following diagrams wherein:

FIG. 1 is a schematic illustration of a data structure employed torepresent an image frame in LCEVC, wherein the data structure includes abase layer, and one or more enhancement layers; optionally, the one ormore enhancement layers each include a plurality of sub-layers; byselectively omitting enhancement layers or sub-layers when LCEVC isemployed in JSCC, bit-rate of data communicated from a given encoder toa given decoder can be conveniently dynamically varied to cope withtransmission interferences, bandwidth limitations and ghosting effects,for example as encountered in wireless communication;

FIG. 2 is a schematic illustration of a data communication systemincluding an encoder, a data communication network, for exampleimplemented wirelessly via one or more wireless channels, for example aplurality of radio channels, and one or more decoders, for example aplurality of decoders; the system operates according to JSCC and a LCEVCdata structure employing a hierarchical representation of image framesis employed when communicating data from the encoder to the one or moredecoders; and

FIG. 3 is a schematic illustration of temporal overlapping employed inthe data communication system of FIG. 2 to reduce an operating latencyof the system.

In the accompanying drawings, an underlined number is employed torepresent an item over which the underlined number is positioned or anitem to which the underlined number is adjacent. A non-underlined numberrelates to an item identified by a line linking the non-underlinednumber to the item. When a number is non-underlined and accompanied byan associated arrow, the non-underlined number is used to identify ageneral item at which the arrow is pointing.

DETAILED DESCRIPTION OF EMBODIMENTS

The following detailed description illustrates embodiments of thepresent disclosure and ways in which they can be implemented. Althoughsome modes of carrying out the present disclosure have been disclosed,those skilled in the art would recognize that other embodiments forcarrying out or practising the present disclosure are also possible.

Low complexity enhancement video coding (LCEVC) is now well knownthrough various published patent applications that hereby incorporatedby reference:

PCT/IB2012/053660; PCT/IB2012/053722; PCT/IB2012/053723PCT/IB2012/053725; PCT/IB2012/056689; PCT/IB2012/002286PCT/IB2013/050486; PCT/EP2013/059833; PCT/IB2013/059847PCT/IB2014/060716; PCT/GB2016/050632; PCT/GB2017/052631PCT/GB2017/052632; PCT/GB2017/052633

LECVC employs a hierarchical structure to represent image data, whereinthere is provided a base layer, together with one or more enhancementlayers having associated therewith residual data. In an encoder, thebase layer is generated by downsampling an input signal and thenencoding the downsampled input signal to generate the base layer.Moreover, in the encoder the downsampled input signal is upsampled andsubtracted from the input signal to generate enhancement layer data.Optionally, in the encoder, data for a plurality of enhancement layerscan be generated, wherein each enhancement layer can have sub-layersrelating to particular image parameters, for example luminosity andcolour. Optionally, the downsampling and upsampling can employ mutuallydifferent functions, such that the downsampling is not merely an inverseof the upsampling; this enables entropy present in the residual data tobe optimized for compression. In the encoder, or a subsequent unit tothe encoder, the base layer data and the enhancement layer data iscombined and then compressed to provide output data for transmissionfrom the encoder to one or more decoders. Such transmission can occur,for example, via a wireless link, for example a wireless satellite datacommunication link.

In a LCECVC decoder, the output data is received and decoded to providea rendition of the base layer. Thereafter, the one or more enhancementlayers are decoded and their associated residual data is applied to therendition of the base layer to enhance a quality of the base layer to ahigh level of quality, for example enhanced resolution, enhanced colourresolution and so forth.

The LCEVC encoder and the LCEVC decoder can be considered together asbeing a LCEVC codec. Such an LCEVC codec is of advantage in that itprovides scalability; in other words, when communicating the output datafrom the encoder to the decoder, certain enhancement layers can beoptionally omitted, and certain residual data can be omitted in order toprovide dynamic bit-rate control to the output data communicated fromthe encoder to the decoder. Moreover, when operation of the codec is notlossless, for example as a result of employing quantization in theencoder when encoding image or video data, quantization parameters canbe dynamically varied in order to provide bit-rate control to the outputdata. Such temporally dynamic operation of LCEVC makes it especiallysuitable for use in systems employing wireless communication, where adata transmission link from a source to a recipient can be temporallyvariable and subject to ghosting and interference. Thus, LCEVC used in acontext of JSCC is able to provide enhanced performance on account ofthe flexible hierarchical manner in which LCEVC functions. Moreover, useof LCEVC in a context of JSCC is capable of providing a lower degree oflatency, because, for a given image frame, the base layer data can becommunicate firstly from the encoder to the decoder for the decoder tostart decoding, while enhancement layer data is then communicated fromthe encoder to the decoder. By employing temporally overlappingcommunication of the layers of LCEVC from a given encoder to a givendecoder, latency can be considerably reduced, for example as depicted inFIG. 1 .

A combination of joint source channel coding (JSCC) and LCEVC, asdescribed in the foregoing, has hitherto not been proposed. Likewise, acombination of JSCC and VC-6 has hitherto not been proposed. Such acombination allows a greater bit-rate control precision to be achievedwhen communicating data from a given encoder to a given decoder via adata communication link, for example a wireless data communication link.Selective dropping of layers in the LCEVC data structure allows for fineprecision control of bitrate for example.

During transmission of the output data from a given encoder, or evenwhen the output data is received at a given decoder, the enhancementprovided by the one or more enhancement layers of LCEVC can be dropped,without need for retransmission of data packets associated with thedropped layers of LVEVC. When this happens, however, it is highlybeneficial to implement a feedback loop signal to the given encoder,which must force an enhancement temporal buffer refresh for a followingimage frame (or an image frame subsequent thereto, if the signal arrivestoo late at the given encoder), in order to avoid ghosted/stickyresiduals in the enhancement layers of LCEVC.

As aforementioned, data of the base layer can be transmitted from thegiven encoder to the given decoder, while data of the one or morecorresponding enhancement layers is still being computed in the givenencoder; this inherently gives priority to data packets of the baselayer, which, if lost in transmission, can be retransmitted (optionally,at an expense of correspond enhancement layer data being dropped fromtransmission from the given encoder to the given decoder).

When communicating data from the given encoder to the given decoder,data associated with a given intra-frame (namely “I-frame”, namely acomplete image frames from which other frames can be derived, forexample from motion estimation implemented in the encoder and decoder)can be spread over a plurality of frames intervals in data communicatedto the decoder; such an implementation reduces peak data rates whencommunicating from the given encoder to the given decoder. Suchspreading worsens an overall average bitrate required to communicatefrom the given encoder to the given decoder, but it dramatically reducesthe size of the I-frame, which is a big driver of buffers as well asoverall latency within the aforesaid system of the present disclosure.However, achieving a low latency, for example less than 50 milliseconds(mS) is highly desirable in video conferencing systems, and inremotely-controlled robotics where a captured image is communicated to aremote location where, for example, an artificial intelligence cognitiveengine AI engine processes the capture image to decide how to respond,for example by controlling actuators. If there is a high degree oflatency, such remote control can function in an unstable or sluggishmanner. In general, implementing JSCC using LCEVC is capable of reducinga data error rate occurring within the aforesaid system, andretransmission of enhancement layer packets can be potentially avoided.

Beneficially, when one or more enhancement layers, and/or one or moreenhancement sub-layers are dropped, a subtle level of dithering isapplied to at least partially reconstruct high frequencies that havebeen lost that would have otherwise being conveyed in these enhancementlayers or sub-layers, for example to avoid visible aliasing at diagonaledges when the image is reconstructed and rendered at the given decoder.Such dithering is option done after encoding, by using a transmissionsystem to intervene in a header of data to be sent from the givenencoder to the given decoder; however, it will be appreciated that sucha transmission system is employed to intervene in order to drop one ormore enhancement layers or sub-layers in anyway. The transmission systembeneficially signals a suitable dither strength/magnitude.

In the aforesaid system, it is much better to reduce the amount ofenhancement data to be communicated on a given frame in order to retaincontrol of quality rather than just forcing a reset; (such a reductionis also important in a situation where whole enhancement data is beingdropped), so that it is feasible to adjust instantly a size of theenhancement data based on a given channel quality to be achieved, whilealways maintaining a base level of quality. Thus, in an event thatcommunicating data of the base layer from the given encoder to the givendecoder, it is beneficial to reduce a size of the enhancement data,which assists to reduce latency arising within the system.

In embodiments of the present disclosure, it is highly beneficial tohave a least two mutually separate elements (namely base layer data in afirst case, and one more enhancement layer data in a second case) whereit is feasible to employ mutually different channel data-bit rates, andmost importantly wherein it is feasible to adjust dynamically thechannel rate and the underlining data bit rate together to maximizequality or minimize latency. For latency reduction purposes, it isdesirable to send a maximum amount of data in a shortest amount of timein a “burst” that does not take a whole ‘video frame’ to send the data,otherwise relatively little latency reduction gain is achieved (apartfrom avoiding resend requests). Moreover, with aforesaid temporallyoverlapping of data transmission of hierarchically structured data asemployed in LCEVC, it is feasible to allow more time for accommodatingtransmission a normal full frame codec would require, thereby enablingan increase in image rendition quality at the given decoder to achieved(namely effectively increases bitrate) without increasing latency.

One potential hierarchical coding algorithm that is optionally used inembodiments of the present disclosure is a proprietary Perseus™ Proproduct from V-Nova International Ltd. (which has byte-stream formatelements that allow for partial and parallel decoding, and that uses astatic entropy decoding rather than an adaptive entropy decoding); aproprietary Perseus™ Pro product from V-Nova International Ltd is alsodescribed in the following US patent applications, which are herebyincorporated by reference:

13/188,188, 13/188,201, 13/188,207, 13/188,220, 13/188,226, 13/352,944,13/188,237, 13/303,554, 13/744,808, 13/893,665, 13/893,669, 13/894,417,13/893,672, 13/893,677, 15/783,204, 15/779,193, 16/077,828, 16/103,784,16/078,352, 16/126,939, 16/252,357, 16/252,362, 16/324,433, 16/324,431,16/295,847, 16/295,851, 16/295,854

as well as in the following PCT patent applications, which are herebyincorporated by reference

PCT/GB2017/053716, PCT/EP2018/075603, PCT/EP2018/082350,PCT/GB2018/053551, PCT/GB2018/053556, PCT/GB2018/053553,PCT/GB2019/050122, PCT/GB2018/053552, PCT/GB2019/051104,PCT/GB2018/053546, PCT/GB2018/053555, PCT/GB2018/053547,PCT/GB2018/053554, PCT/GB2018/053548.

It is to be understood that any feature described in relation to any oneembodiment may be used alone, or in combination with other featuresdescribed, and may also be used in combination with at least one featureof any other of the embodiments, or any combination of any other of theembodiments. Furthermore, equivalents and modifications not describedabove may also be employed without departing from the scope of theinvention, which is defined in the accompanying statements.

1. (canceled)
 2. A data decoding system comprising: at least onedecoder; wherein the system is communicatively coupled to a datacommunication network; wherein the system is configured to receiveencoded data from an encoder and the at least one decoder is configuredto decode the received encoded data; wherein the received encoded datahas been encoded in an hierarchical data structure for representing datato be communicated from the encoder to the at least one decoder, whereinthe hierarchical data structure includes a base layer and one or moreenhancement layers with associated residual data, wherein the base layeris capable of providing a coarse rendition of the input signal at the atleast one decoder, and the one or more enhancement layers and theirassociated residual data are useable when received at the least onedecoder to enhance the coarse rendition to render the input signal at ahigher level of quality than the coarse rendition; and wherein the atleast one decoder is configured to receive and decode lower level datawhen parts of data of the one or more enhancement layers and theirassociated residual data have been selectively dropped by the encoder inresponse to bandwidth limitations, ghosting, interference and/or dataerrors arising in the data communication network.
 3. The data decodingsystem of claim 2, wherein the at least one decoder is configured toreceive base layer data of a given image frame to decode concurrentlywith the encoder computing enhancement layer data of the given imageframe to send subsequently to the at least one decoder, thereby reducinga latency of data communication arising when communicating from the atleast one encoder to the at least one decoder.
 4. The data decodingsystem of claim 2, wherein the at least one decoder is configured toreceive resent base layer data when the encoder has dropped enhancementlayer data of a given image frame in an event that a first transmissionof the base layer data of the given image frame was corrupted whenreceived by the at least one decoder.
 5. The data decoding system ofclaim 2, wherein the system is configured to receive data of a givenIntra-frame of the input signal which has been spread into a pluralityof frame durations when communicated from the encoder to the at leastone decoder.
 6. A method of receiving and decoding data at a datadecoding system that includes at least one decoder, the methodcomprising: the at least one decoder receiving encoded data from anencoder; the encoded data having been encoded by the encoder in anhierarchical data structure for representing data to be communicatedfrom the encoder to at least one decoder, wherein the hierarchical datastructure includes a base layer and one or more enhancement layers withassociated residual data, wherein the base layer is capable of providinga coarse rendition of the input signal at the at least one decoder, andthe one or more enhancement layers and their associated residual databeing useable when received at the least one decoder to enhance thecoarse rendition to render the input signal at a high level of qualitythan the coarse rendition; the at least one decoder configured toreceive and decode lower level data when parts of data of the one ormore enhancement layers and their associated residual data have beenselectively dropped by the encoder in response to bandwidth limitations,ghosting, interference and/or data errors arising in the datacommunication network; and the decoder decoding the received encodeddata.
 7. The method of claim 6, wherein the method further comprises thedecoder receiving base layer data of a given image frame and decodingthe base layer data concurrently with the encoder computing enhancementlayer data of the given image frame to send subsequently to the at leastone decoder, thereby reducing a latency of data communication arisingwhen communicating from the at least one encoder to the at least onedecoder.
 8. The method of claim 6, wherein the method further comprisesreceiving resent base layer data when the encoder has droppedenhancement layer data of a given image frame in an event that a firsttransmission of the base layer data of the given image frame wascorrupted when received by the at least one decoder.
 9. The method ofclaim 6, wherein the method further comprises receiving data of a givenIntra-frame of the input signal which has been spread into a pluralityof frame durations when communicated from the encoder to the at leastone decoder.
 10. A computer program product comprising a non-transitorycomputer-readable storage medium having computer-readable instructionsstored thereon, the computer-readable instructions being executable by acomputerized device comprising processing hardware to execute the methodof claim 6.